Effect of diazepam and midazolam on the antinociceptive effect of morphine, metamizol and indomethacin in mice.

The influence of midazolam and diazepam on antinociceptive effect of morphine (10 mg/kg), metamizol (500 mg/kg) and indomethacin (10 mg/kg) was investigated in a mouse model using the tail-flick and hot-plate tests. All drugs were injected intraperitoneally. Benzodiazepines were administered to mice 30 min before applying the analgesic drugs. Measurement of nociception was performed within 2 h after benzodiazepine administration. Diazepam at doses of 0.25 mg/kg and 2.5 mg/kg injected with morphine was found to decrease the antinociceptive effect of morphine. Similarly, diazepam decreased the antinociceptive effect of metamizol (only in the tail-flick test) and indomethacin. Midazolam used at doses of 1.25 mg/kg and 2.5 mg/kg decreased the antinociceptive effect of morphine, metamizol (only in the tail-flick test) and indomethacin.